JPS6050772B2 - Method for producing methyl-norbornane derivative - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the following formula (I): This invention relates to a method for producing a novel methylnorbornane derivative represented by ')'.

Compound I produced by the method of the present invention has a sandalwood-like odor with green notes, and is an important compound as a perfume.

Natural sandalwood oil is an oil obtained by steam distilling the heartwood and roots of sandalwood trees grown in the Malay region of India, and is an important flavoring agent for oriental flavor preparations.

However, sandalwood is a special plant that produces suckers that are longer than its roots and grows parasitic on the roots of other trees.It takes three hours to cultivate sandalwood oil from seeds and collect sandalwood oil. However, as resources have become scarce, there has been a shortage of supply in recent years, making it expensive. Also,
The main component of natural sandalwood oil is α, β-santalol, and the industrial production method for this has not been successful.Therefore, it is desired to develop a synthetic fragrance with a similar aroma, and the odor will be reduced. Several products similar to sandalwood oil but with completely different structures are available on the market, but these too do not satisfy the public demand in terms of price and aroma. Therefore, the present inventor conducted intensive research in order to meet such demand, and as a result, obtained a method that is industrially easy to carry out to produce a product from meth,8-methylcyclopentadiene that has an aroma similar to that of α,β-santalol (1 ) We succeeded in synthesizing a new compound of the formula.

The reaction formula for the production method of the present invention is as follows.

That is, in the present invention, methylcyclopentadiene (■) and acrolein (2) are reacted by a Diels-Alder reaction to form an adduct (2), which is hydrogenated to form methylnorbornane carbaldehyde (2), which is reacted in the presence of an alkali. There is a method for producing methyl norbornane derivative 1 by condensing diethyl ketone (1) and then reducing this product (2). Methylcyclopentadiene used as a raw material in the present invention is an unstable compound and is usually commercially available as a dimer.

If this dimer is heated to 180°C, a mixture of 2-methyl and 3-methyl forms at a ratio of 1:1 can be obtained, but these are difficult to separate even by distillation or the like.

(V.A.MIRONOV et al. '4Tetrahedr
0n'5V01.19, pp1939) However, in the present invention, this mixture can be used to achieve the purpose, and hereinafter the 1:1 mixture of 2-methyl and 3-methyl is simply referred to as methylcyclopentadiene. do. In the present invention, first, methylcyclopentadiene and acrolein are reacted by a Diels-Alder reaction to obtain an adduct.

It is composed of a mixture of adducts as shown in the following reaction equation. Although these are difficult to separate, they can be used industrially as a mixture to achieve their purpose as fragrances.

The Diels-Alder reaction was performed by R. Adams;″0rga
nicReacti0ns0V01. ■, SecOnd
It can be carried out under the reaction conditions described in printing May, 1949, pp 89-90. In other words, simply mixing equimolar amounts of both five compounds at room temperature generates heat, so the mixture is cooled and kept at room temperature. As the solvent used in this step, benzene, toluene, diethyl ether, and tetrahydrofuran can be used. This adduct is then catalytically hydrogenated using hydrogen and a catalyst such as palladium to give a norbornane derivative.

This reaction is carried out in a solvent such as cyclohexane using a palladium catalyst, e.g., a palladium-activated carbon catalyst containing 5% palladium by weight, in an amount of about 1% of the raw material compound, and a theoretical amount of hydrogen under a hydrogen pressure of 5 to 10 kt/CTI. Allow to react until absorbed. When the hydrogenation is completed, the reaction solution is passed through a p-filter to remove the catalyst, the solvent is distilled off, and the norbornane derivative is obtained by distillation under reduced pressure. Next, this and diethyl ketone are condensed in the presence of an alkali to obtain a ketone compound (2).

The condensation is carried out in a solvent such as methanol in the presence of an alkali, such as caustic soda or caustic potash, by heating to reflux for 2 to 3 hours. Diethyl ketone has a ratio of 2.5 to the adduct
~3 equivalents are used. Caustic alkali is 114 against adducts.
It is preferable to use an equivalent amount and use it as a 0.3N methanol solution of caustic alkali. After the reaction, methanol is recovered under reduced pressure, the concentrate is dissolved in ether, washed with saturated brine, the ether is distilled off, and the residue is distilled under reduced pressure to obtain a ketone compound. Ketone compounds consist of a mixture of isomers, but it is difficult to separate these isomers, and industrially they can be used as a mixture for perfume purposes.
Next, the carbonyl group of the ketone compound is reduced using sodium borohydride or lithium ariminium hydride to obtain the desired methylnorbornane derivative.

When using sodium borohydride, use 1.5 equivalents of sodium borohydride to the ketone compound (equivalent to 0.38 mol to 1 mol of the ketone compound),
The reaction is preferably carried out in aqueous methanol, and caustic alkali is added to prevent decomposition of the sodium borohydride.
Caustic alkali is 10% of sodium borohydride.
It is sufficient to use ~15% by weight. Methanol is used in an amount of at least 1.5 to 2 times the amount of the ketone compound. The higher the number, the better. Water is used to the extent that methanol becomes 75% aqueous methanol. 1.5-2 at 40'C
Give it time to react.

After completion of the reaction, methanol is recovered under reduced pressure, the residue is dissolved in toluene, washed with saturated brine, the toluene is distilled off, and the target compound is purified by distillation under reduced pressure. When using lithium aluminum hydride to reduce a ketone compound, the amount of lithium aluminum hydride used is 1.5 equivalents (equivalent to 0.38 mol per 1 mol of the ketone compound), and 10 times the amount of anhydrous diethyl ether is used as a solvent. The reaction is carried out at 5-10°C under ice cooling.
After the reaction is complete, water is added to decompose the remaining lithium aluminum hydride, the ether layer is dried over anhydrous sodium sulfate, the ether is distilled off, and the target compound is obtained by distillation under reduced pressure. The methylnorbornane derivative thus obtained is 1-(1′-methylnorborn-2″-yl)-2-methylbent-1-en-3-ol, 1-(
45-Methylnorborne-2''-yl)-2-methylbent-1-en-3-ol, 1-(5'-methylnorborne-2'-yl)-2-methylbent-1-en-3-ol, It is a mixture of 1-(6″-methylnorborn-2″-yl)-2-methylbent-1-en-3-ol, and the aroma of these compounds is derived from α,β-santa, which is the main component of sandalwood oil. These compounds have an aroma similar to that of rolls, and can be industrially advantageously used as a fragrance component without being separated into individual components (even as a mixture).

Next, an example will be given and explained.

Example 1J (1) Put 400 g of methyl-cyclopentadiene and 1 q of hydroquinone into a 3' reaction flask, and add 311 y of acrolein and 440 ml of tetrahydrofuran to it while stirring under ice cooling.
The mixture of mt was added dropwise over a period of 2 hours while maintaining the internal temperature at 25 to 300C, and the mixture was further reacted at the same temperature for 3 hours.

After the reaction, the contents were transferred to a distillation flask, and after distilling off tetrahydrofuran, it was distilled under reduced pressure to 70-72°C/15°C. H
A fraction of g was obtained, namely an adduct of methyl-cyclopentadiene and acrolein, 658.1y. This thing is I
It was R4 (1710 cm-1,715α-1). (
11) Adduct 27.2y1 cyclohexane 27 obtained above
m1, 5% palladium-activated carbon catalyst 0.27y 200
Place in a mL autoclave and apply hydrogen pressure of 5 to 10 k under water cooling.
Hydrogenated with 9/CIL. The reaction stopped after absorbing the theoretical amount of hydrogen. After the reaction solution was filtered to remove the catalyst, cyclohexane was distilled off under reduced pressure to obtain 27.9 das of methylnorbornane carbaldehyde as a residue. (iii)
A 300 ml reaction flask was charged with 5 y of 40% caustic soda solution, 150 ml of methanol, and 46 y of diethyl ketone, and while heating under reflux, 27.9 y of the methylnorbornane carbaldehyde obtained above was added dropwise over 15 minutes, and the mixture was further heated under reflux for 2 hours. .

Methanol was distilled off under reduced pressure, and 100% of ether was added to the concentrate.
After washing with 100 ml of saturated brine three times, the mixture was transferred to a distillation flask and the ether was distilled off. The residue was distilled under reduced pressure to obtain a fraction of 85-9rc/1.7 order Hg, ie, a ketone compound, 27.5y. IR:1660
cm-1. iv) Put the fraction 13y obtained above into a 200ml reaction flask, add 130mt of ether, and add 1.5y of lithium aluminum hydride while stirring under ice cooling.
Add little by little, then 1. Allowed time to react.

Water was added to the reaction solution to decompose it with stirring, and the ether layer was separated, dried over anhydrous sodium sulfate, and then the ether was distilled off. The residue was distilled under reduced pressure to 86-91℃/1.0T! r! NHg fraction, i.e. the desired methylnorbornane derivative, 9
．． I got 0y. The 1R and NMR spectra of the methylnorbornane derivative thus obtained are shown in Figures 1 and 2.
As shown in the figure. ? Example Using the methylnorbornane derivative obtained in Example 1, a blended perfume for eau de cologne was produced according to the following recipe.

Prescription) Part by weight Example 1
220 Sandalwood oil 70 Vanillin
3 ethyl vanillin
2 Labranum Absolute
20 Acetyl Cedrene 100 Oakmoss Absolute 30 Isobutylquinoline (10%) 20 γ-Methyl Ionone 50 Hydroxycitronellal 60 α-Hexyl Cinnamic Aldehyde 90 Diasmine Base
50 Benzyl Acetate Ylang Ylang Oil Phenylethyl Alcohol Rose Base Aldehyde Cll (10%) Galbanum Oil Bergamot Oil 1000 The aroma of this product was a pleasant one with a midday-type oriental tone.

[Brief explanation of the drawing]

FIG. 1 shows the ■R spectrum of the methylnorbornane derivative obtained in Example 1, and FIG. 2 shows the NMR spectrum of the same compound.

Claims (1)

[Claims] 1. Methylcyclopentadiene and acrolein are reacted by a Diels-Alder reaction to form an adduct, which is hydrogenated to form methyl-norbornane carbaldehyde, and diethyl ketone is added to this in the presence of an alkali. There are the following formulas (I), ▲mathematical formulas, chemical formulas, tables, etc.▼(I), which are characterized by condensation and then reduction of this product. , indicating substitution at either the 5' or 6' position).